<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
      <style type="text/css">
      #s2{ 
      color:green;
      
      }
      .D{
           color:red;
      }
      
      .c2{
         color:yellow;
      }
       li,h3,#s2{
         background-color:pink;
         }
     input[type='submit']{
         background-color:blue;
        }
    
      </style>
</head>
<body>
    <div>div1</div> <div>div2</div> <div class="D">div3</div>
    <span>span1</span> <span id="s2">span2</span> <span class="D">span3</span>
    <h3 class="D">h3</h3>
    <input type="button" value='按钮'>
    <input type="submit">
    <ul>
       <li class="c2">北京<li>
       <li>上海<li>
       <li class="c2">广州<li>
    </ul>  
</body>
</html>